1. Field of the Invention
The present invention relates to a reflex-type screen for displaying an image which is projected from a projector, and a reflex-type screen assembly equipped with the reflex-type screen.
2. Description of the Related Art
Conventionally, there has been a demand for displaying an image on a screen for an observer located just in front of the screen by projecting the image onto the reflex-type screen at an angle in a short range. When a widely used white mat reflex-type screen is used for the purpose, since majority of the image light projected from the short focal-length projector is reflected to a place where the observer is not present, an even and bright image cannot be provided to the observer located just in front of the reflex-type screen.
For example, as a reflex-type screen that solve the above-mentioned drawbacks, Japanese Patent Laid-Open No. 2000-347297 and Japanese Patent Laid-Open No. 2000-241888 disclose a hologram reflecting screen using hologram element on a reflection plane, which diffuses and diffracts the projected image light towards the observer. In addition, Japanese Patent Laid-Open No. H11-44805 discloses a transparent resin panel on which a shading film is formed, where the cross section of the panel has saw-tooth appearance formed by vertical planes and inclined planes which are provided alternately, as a technique to reduce the reflection of a light on a transparent cover provided, for example, in front of instruments of an automobile.
However, the hologram element of the hologram reflex-type screen has a limit of chromatic dispersion. Therefore, when the image light (e.g., image light projected from a projector) including a predetermined wavelength range is projected, a color shift may occur, for example, in periphery of the screen due to the chromatic dispersion of the hologram element.
Moreover, the hologram element records hologram information by exposing photosensitive resin, or so-called exposing method. When the exposing method is to be employed, it is difficult to enlarge the size of the screen due to the restrictions on a manufacturing method. Moreover, in order to make angle-of-visibility property in a vertical direction being different from that in a horizontal direction, multiple exposure is needed which makes the manufacturing method more complicated.
Moreover, when the transparent resin panel disclosed in Japanese Patent Laid-Open No. 11-44805 is to be employed to the reflex-type screen, there is a problem that it is difficult to give the reflectivity and diffusivity required for the reflex-type screen on a saw-tooth cross section.